After updating TeX Live today, recompiling the xpeek documentation
gives “0” as the page number for all commands in the index, and “1” as
the line number for all definitions. The hyperlinks point to the
correct places, though.

The version info in l3doc is “This file has version number v4070, last
revised 2012/08/09.”  There does not seem to be any substantial
difference in l3doc.dtx on GitHub recently, so this might well be a
bug in one of the other recently-updated packages: any likely